The compact case has a hinge structure to cover with a lid body in an openable and closable manner an opening of a flat box-shaped container body to be a storage space of cosmetics and cosmetic tools. There is a compact case that is urged, with a special hinge structure, in a direction in which the lid body opens automatically when the lid body is opened to a certain angle or greater than such an angle, and that is urged in a direction in which the lid body closes when the angle is smaller than such an angle. Further, there are also compact cases that can hold the lid body at a predetermined angle in such a state. With such a compact case, it is not necessary to separately provide a mechanical structure (such as a hook) to maintain the lid body in a closed state, and the compact case has features that its opening and closing operation is easy and also has an excellent outer appearance.
With this type of compact case, the container body and the lid body are connected with a hinge (hereinafter referred as a hinge unit) that can control a rotational torque, in order to automatically open and close the lid body in accordance with the opening and closing angle. The hinge unit has generally a structure in which a shaft section is protruded from one end surface of a tubular case section to be rotatable about the axis of the tubular case section, and the case section contains therein a rotational torque control mechanism to control the rotational torque of the shaft section.
Note that, in PTLs 1 and 2 below are disclosed a structure of the hinge unit, and a structure of the compact case (compact case built-in with the hinge unit) using such a hinge unit. For example, the hinge in the compact case built-in with the hinge unit described in PTL 1 is a structure in which a hinge section of the container body is sandwiched by hinge sections of the lid body, both hinge sections are arranged coaxially, and the hinge unit is inserted toward the hinge section of the container body from the outer side of the hinge section of the lid body. That is, the case section of the hinge unit is inserted in the hinge section of the container body, and the shaft section of the hinge unit is protruded inside the hinge section of the lid body. Further, the hinge section of the lid body is closed up from the outer side with a cap member to fix the shaft section to the lid body. In this way, the shaft section of the hinge unit is fixed to the hinge section of the lid body, the case section is fixed to the hinge section of the container body, and the lid body and the container body are connected via the hinge unit. Note that, the cap shaped part is fitted in the lid body so that the hinge unit itself does not inadvertently fall out of a through hole.
Further, with the compact case built-in with the hinge unit disclosed in PTL 3 below, a through hole is formed in the hinge section of the container body and a recessed receiving section is formed in the lid body, and the hinge section of the container body is positioned to the outer side of the hinge section of the lid body. With such a compact case built-in with the hinge unit, after inserting the hinge unit from the through hole and connecting the lid body and the container body, an opening of the through hole is closed up, and further a cover member forming a bottom surface of the compact case built-in with the hinge unit is assembled. In PTL 4 below, there is described a compact case with a built-in hinge unit that can make the tip end of the hinge unit be easily fitted in a hole formed in the container body or the lid body and in which workability is improved when assembling, by using the hinge unit that has a hemispheric tip end.